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Oxford System

Oxford system is a very comprehensive system of classifying and grading cataracts. It  includes quantitation on a scale of zero to 5 of such features as anterior clear zone thickness, anterior subcapsular opacity, posterior subcapsular opacity, cortical spoke opacity, waterclefts, vacuoles, retrodots, focal dots, nuclear brunescence, and white nuclear scatter.22 The system gives the anterior clear zone thickness reference standards, the diameter scale reference standards for grading anterior and posterior subcapsular opacities,  the pie segment reference standards for grading spoke opacities and waterclefts, the vacuole reference standards, the retrodot reference standards, the focal dot reference standards. 22 Nuclear brunescence is graded by comparing the posterior region of the nucleus just anterior to the posterior nuclear shell with a set of Munsell color chips. The grade is selected according to the closest available match between the nucleus and the color chips 22 White nuclear scatter is assessed as the amount of white light being scattered back to the observer by the lens nucleus and is compared with Munsell neutral-density gray-scale samples 22

Japanese Cooperative Cataract Epidemiology Study Group System

The Japanese Cooperative Cataract Epidemiology Study Group system also uses a set of standard photographs in grading cortical, nuclear, and subcapsular opacities.24 These cataracts are graded as early (I), moderate (II), or advanced (III). and  give the standard photographs of cortical and nuclear cataract, respectively. 24 An opacified area corresponding to the normal pupil size is graded I; an area larger than a normal pupil but smaller than a moderately dilated pupil as II; and one larger than a moderately dilated pupil as grade III. Subcapsular opacities are graded in reference to the pupil size. Nuclear coloration is classified into four gradings: I, pale yellow; II, yellow; III, brownish-yellow; IV, brown (including reddish-brown and black-brown The Japanese Cooperative Cataract Epidemiology Study Group system also uses a set of standard photographs in grading cortical, nuclear, and subcapsular opacities

World Health Organization's Simplified Cataract Grading System

There had been so many classification systems with their own merits and demerits so in an attempt to unify the methods of grading age-related cataract and produce a simplified version of present grading systems, the WHO in 1996 convened a meeting of most of the clinicians and epidemiologists with cataract classification expertise. The charge to this group was to design, implement, and validate a new system of classifying age-related cataract using the strengths of the existing systems of cataract classification. This goal has been largely achieved and at present this system is undergoing field testing in Australia. When testing is completed, test results and details of the system will be published.
Recent Attempts at Classification Of Cataracts

A study was published in British Journal of Ophthalmology in 2008, which set to find out the correlation of lens density measured using the Pentacam Scheimpflug system with the Lens Opacities Classification System III grading score. It incorporated 180 eyes of 138 patients whose visual acuity was testing using the ETDRS chart and the LOCS III grading and Pentacam evaluation was done.  It was found out that there was a linear increasing relationship between lens density value and LOCS III grading score in nuclear cataract patients. Lens density value had a stronger significant correlation with LOCS III NO score than that with NC score. The correlation between the nuclear lens density value and log MAR visual acuity was stronger than that between NO score and log MAR visual acuity or between NC score and log MAR visual acuity 25

Another study published in Ophthalmology in 200926 also proved the correlation of LOCS III with pentacam Schiempflug imaging system. 110 patients were enrolled in the study and it was found out that certain areas of nucleus are more representative of the lens density on schiempflug imaging (region of interest), and that these areas correlated with the LOCS III, whereas the Average Lens Density measurement on Pentacam did not correlate with the LOCS III standards. (Figures 1-3)

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Figure 1 : Oculus Pentacam

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Figure 2: The figure shows a Region Of Interest(ROI) being measured with the help of ImageJ software

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Figure 3: The figure shows Average Lens Density being measured with the help of ImageJ software

 

References

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2. Truscott RJW, Augusteyn RC: Changes in human lens proteins during nuclear cataract formation. Exp Eye Res 1977; 24:159

3. Marcantonio JM, Duncan G, Davies PD, et al: Classification of human senile cataracts by nuclear colour and sodium content. Exp Eye Res 1980; 31:227

4.Chylack LT Jr: Classification of human cataracts. Arch Ophthalmol , 1978
; 96:888

5.Chylack LT Jr, Lee MR, Tung WH, Cheng HM: Classification of human senile cataractous change by the American Cooperative Cataract Research Group (CCRG) method. I: Instrumentation and technique. Invest Ophthalmol Vis Sci 1983; 24:424

6. Chylack LT Jr, Lee MR, Tung WH, Cheng HM: Classification of human senile cataractous change by the Americal Cooperative Cataract Research Group (CCRG) method. I: Instrumentation and technique. Invest Ophthalmol Vis Sci , 1983; 24:424

7. Chylack LT Jr, Wolfe JK, Singer DM, et al: The Lens Opacities Classification System III. The Longitudinal Study of Cataract Study Group. Arch Ophthalmol 1993; 111:831–836

8.Duncan G: On classifying human cataractous lens. In Duncan G (ed): Mechanisms of Cataract Formation in the Human Lens. Orlando, FL, Academic, 1981.

9. Leske MC, Sperduto R: The epidemiology of senile cataracts: A review. Am J Epidemiol, 1983; 118:152,

10. West SK, Taylor HR: The detection and grading of cataract: An epidemiologic approach. Surv Ophthalmol , 1986; 31:175

11. Baez KA, Orengo S, Gandham S, Spaeth GL: Intraobserver and interobserver reproducibility of the Nidek EAS-1000 Anterior Eye Segment Analysis System. Ophthalmic Surg , 1992; 23:426–428

12.Chylack LT Jr, Leske MC, McCarthy D, et al: Lens Opacities Classification System II (LOCS II). Arch Ophthalmol, 1989; 107:991.

13 Chylack LT Jr, Leske MC, Sperduto R, et al: Lens Opacities Classification System. Arch Ophthalmol , 1988; 106:330

14. Taylor HR, West SK: A simple system for the clinical grading of lens opacities. Lens Res , 1988; 5:175

15. Adamsons I, Taylor KI, Enger C, Taylor HR: A new method for documenting lens opacities. Am J Ophthalmol, 1991 111:65–70

16. Adamsons I, Munoz B, Enger C, Taylor HR: Prevalence of lens opacities in surgical and general populations. Arch Ophthalmol , 1991; 109:993–997

17. Lee JA and Taylor HR: Evaluation of photographic methods for documentation of lens opacities. Invest Ophthalmol Vis Sci, 1990 31:1191–1193

18. Taylor HR, Munoz B: The incidence and progression of lens opacities. Aust N Z J Ophthalmol, 1991; 19:353–356

19. West SK, Rosenthal F, Newland HS, et al: Use of photographic techniques to grade nuclear cataracts. Invest Ophthalmol Vis Sci, 1988 29:73

20. Sasaki K, Shibata T, Obazawa H, et al: A cataract classification and grading system. Nippon Ganka Gakkai Zasshi 1989; 93:796–800

21. Sasaki K, Sakamoto Y, Fujisawa K, et al: A new grading system for nuclear cataracts—An alternative to the Japanese Cooperative Cataract Epidemiology Study Group's grading system. Dev Ophthalmol , 1997;
27:42–49

22. Sparrow JM, Bron AJ, Brown NAP, et al: The Oxford clinical cataract classification and grading system. Int Ophthalmol, 1986; 9:207–225

23. Leske MC, Chylack LT Jr, Wu SY, et al: The lens opacities case-control study: Risk factors for cataract. Arch Ophthalmol , 1991; 109:244

24. Sasaki K, Shibata T, Obazawa H, et al: Classification system for cataracts: Application by the Japanese Cooperative Cataract Epidemiology Study Group. Ophthalmic Res , 1990; 22(Suppl 1):46.

25. X Pei, Y Bao, Y Chen and X Li : Correlation of lens density measured using the Pentacam Scheimpflug system with the Lens Opacities Classification System III grading score and visual acuity in age-related nuclear cataract. British Journal of Ophthalmology 2008;92:1471-1475

26. Dilraj S. Grewal , Gagandeep S. Brar, Satinder Pal Singh Grewal :Correlation of Nuclear Cataract Lens Density Using Scheimpflug Images with Lens Opacities Classification System III and Visual Function. Ophthalmology 2009;116:1436-1443

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